fitzgerald



Sept. 27, 1927. 1,643,808

v v F. A. J. FITZGERALD ELECTRIC FURNACE Filed June 1, 1925 """HM 1mm.

.Zlnvmto'c Patented Sept. 27, 1927.

UNITED STATES PATENT OFFICE.

FRANCIS A. J. FITZGERALD, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO HARPERELECTRIC FURNACE CORPORATION, A CORPORATION OF NEW YORK.

ELECTRIC FURNACE.

Application filed June 1, 1925.

This invention relates to a furnace and particularly to the type offurnace wherein material being heated is located at some dis tance fromthe source of heat and is heated from such source by conduction orconduction and radiation. The primary object of my invention is toprovide an improved furnace structure whereby a considerable quantity ofmaterial may be quickly raised to a temperature which is uniformthroughout its mass. ther objects of my invention will appear from thefollowing description, taken in connection with the accompanying drawingwhich represents diagrammatically, partly in vertical transverse sectionand partly in elevation, an electrically heated tunnel kiln embodyingone form of my invention.

Referring to the drawing, 1 represents the outer casing of the furnace,2 the tunnel through which is passed the car or cars 3 carrying thematerial 5 to be sub ected to heat-treatment. The resistor l, heated bythe passage of an electric current, radiates its heat to the septum 6which forms the cover or roof of the tunnel, and this septum in turnradiates heat to the material 5 carried through the tunnel on cars 3.

As furnaces of this type are ordinarily constructed, the top of thematerial carried on a car will heat more rapidly than its lowerportions, for the reason that the top is much nearer to the source ofheat-supply. To overcome this disadvantage, I form a lining 7 for theupper portion of the tunnel and the roof of the tunnel of highheatconducting refractory material, so that heat absorbed from theresistor by the tunnel roof will be conducted down the sides of thetunnel 2 through the side lining 7 and will be radiated laterally to thematerial carried by the truck 3. As a material for lining the tunnel andforming the roof 6, I preferably Serial No. 33,924.

employ re-crystallized silicon carbide, the inner lining of the tunnelbeing preferably formed of bricks or tiles ofthat material, and I alsoprovide baflies 8 which extend laterally into recessed portions formedin the truck body and so provide means whereby heat may be radiatedupwardly to the material being heated.

lVhile I have shown my invention as applicable to tunnel kilns, it isobvious that it is also applicable to muffle furnaces or any otherfurnace of this general type.

I claim:

1. In an electric furnace the combination With an outer casing having aresistor chamber confined to its upper portion, of a resistor extendingthrough said chamber and radiating heat downward, article conveyingmeans at the lower portion of the space within said casing, and a heatconducting structure to distribute the heat supply to the articles onsaid conveying means comprising side members of heat conducting materialextending downward along the sides of the casing to a point below thearticles and a septum member ofheat conducting material between thearticles and said resistor chamber.

2. In an electric furnace the combination with an outer casing having aresistor chamber confined to its upper portion, of a re- ;sistorextending through said chamber and radiating heat downward, articleconveying means at the lower portion of the space within said casing,and a heat conducting structure to distribute the heat supply to thearticles on said conveying means com prising side members of siliconcarbide extending downward along the sides of the casing to a pointbelow the articles and a septum member of silicon carbide between thearticles and said resistor chamber.

FRANCIS A. J. FITZGERALD.

